1. Field of the Invention
The present invention relates to a multidimensional link structure of a data communication network. The present invention can be applied to all data communication networks including a public communication network such as the Internet, an Inter-corporate network such as a WAN or Extranet, a Local Area Network, a computer network, a distributed computer network, a distributed router network, an Exchange Network, a Switch Network that is constructed in a router or an electronic device, a network that is constructed in a circuit substrate for a connection between a Central Processing Unit (CPU) and a memory, and a network that is constructed in an Integrated circuit.
2. Description of Related Art
A data communication network is capable of connecting a plurality of nodes. Using a data communication network allows the processing of a plurality of nodes to be distributed and the processing efficiency to be improved.
Known link structures for a data communication network are, for example, the bus structure, ring structure, the hub structure (that is, the star structure), and the full mesh structure. These link structures can be expanded in two dimensions, three dimensions or a greater number of dimensions. A link structure that has been made multidimensional is known as a hyperlink structure.
In order to cope with the increase in the traffic of data communication networks, the maximum value of the traffic that the data communication network is capable of processing, that is, the traffic-handling performance must be increased. As a method for increasing the traffic-handling performance, an increase in the number of nodes contained in the data communication network, an increase in the total number of links contained in the data communication network, and the adoption of a link structure having a high traffic-handling performance may be considered. On the one hand, an increase in the traffic-handling performance is desirably implemented at minimum cost. In order to keep costs low, the traffic-handling performance must be efficiently increased using a number of nodes and a total link number that are as small as possible. 2004 NICT Contract Research and Development report ‘Research and Development of Optical access network high speed wide area communication technology relating to photonic networks’, National Institute of Information and Communications Technology, May 2005, pages 280 to 308 and pages 513 to 522 is known, for example, as a document that discloses the relationship between the number of nodes, total link number and link structure and the traffic-handling performance.
FIG. 1 is a graph that shows the relationship between the number of nodes and the traffic-handling performance. In FIG. 1, the vertical axis is the number of nodes contained in the data communication network and the horizontal axis is the traffic-handling performance of the whole data communication network. The traffic-handling performance is given by the product of the processing performance for each single node and the number of nodes. In FIG. 1, the reference number assigned to each curve indicates the type of link structure and the hyper degree. B is a bus structure, R is a link structure, H is a hub structure, and F is a full mesh structure. For example, B1 is a one-dimensional bus network and R2 is a two-dimensional ring network.
In FIG. 1, link structures with smaller inclinations are able to obtain a high traffic-handling performance with a small number of nodes and therefore high traffic efficiency. For example, a one-dimensional full mesh structure F1 and two-dimensional hub structure have a very high traffic efficiency and a one-dimensional bus structure and a one-dimensional ring structure have a very low traffic efficiency.
FIG. 2 is a graph that shows the relationship between the total number of links and the traffic-handling performance. In FIG. 2, the vertical axis is the total number of links contained in the data communication network and the horizontal axis is the traffic-handling performance of the whole data communication network. The significance of the traffic-handling performance and the significance of the reference numbers assigned to each curve are the same as those of FIG. 1.
In FIG. 2, link structures with smaller inclinations are able to obtain a high traffic-handling performance with a small number of nodes and therefore high traffic efficiency. For example, a four-dimensional hub structure H4 has very high traffic efficiency and a one-dimensional bus structure B1 and a one-dimensional ring structure R1 has very high traffic efficiency.
As can be seen from FIGS. 1 and 2, in general, link structures for which the ratio ‘traffic’/‘number of nodes’ is high have a low ‘traffic’/‘total node number’ ratio and link structures for which the ratio ‘traffic’/‘total number of links’ is high have a low ‘traffic’/‘number of nodes’ ratio. In other words, link structures for which both the ‘traffic’/‘number of nodes’ ratio and the ‘traffic’/‘total number of links’ ratio are optimal do not exist.
FIG. 3A is a graph showing the relationship between the traffic-handling performance and the cost performance. FIG. 3B is a partial enlargement of FIG. 3A. In FIGS. 3A and 3B, the vertical axis is the cost performance of the network configuration, that is, the ratio TNC/T between the total network cost TNC and the traffic-handling performance T. The horizontal axis is the traffic-handling performance T, the units of which are terabits per second. The significance of the traffic-handling performance and the significance of the reference numbers assigned to each curve are the same as those in FIG. 1. For example, in the case of a four-dimensional hub structure H4, the network construction costs when TNC/T=23 and T=1000 are 2.3 trillion Japanese yen.
As can be seen from FIGS. 3A and 3B, the link structure and hyper degree for the optimal cost and performance vary depending on the required traffic-handling performance T.